Recently, three-dimensional screen images and three-dimensional screen image-related apparatuses, such as 3D cinemas and 3D displays, have rapidly come into widespread use. Although shooting of a three-dimensional screen image has also conventionally been performed by a film camera or the like, along with widespread use of a digital image pickup apparatus, such as a digital camera or a digital video camera, images from which a three-dimensional image is produced also have come to be shot using the digital image pickup apparatus.
In a mechanism used for viewing a three-dimensional screen image, a “right-eye image” and a “left-eye image” having parallax in the horizontal direction are prepared such that the prepared images correspond to respective images of an object to be viewed (target object) as viewed with a right eye and a left eye, respectively. Then, the “right-eye image” and the “left-eye image” are viewed with a right eye and a left eye of a viewer, respectively.
As a technique used for this mechanism, there has been known a technique in which an image to be viewed is subjected to parallax division e.g. by a so-called parallax barrier method or a lenticular method. Further, there has also been known a technique of causing different images to enter a left eye and a right eye, respectively, through left and right filters different in characteristics therebetween.
On the other hand, as a technique of shooting images which can be viewed as a three-dimensional screen image, there has been known a technique of simultaneously shooting images from different viewpoints.
For example, there has been proposed a technique in which a plurality of micro lenses are formed on a solid-state image pickup device, and at least one pair of photo diodes is disposed at a location close to each of the micro lenses (see e.g. PTL 1). In this technique, a first image signal is obtained from an output from one photo diode of a photo diode pair, and further, a second image signal is obtained from an output from the other photo diode of the photo diode pair. Then, the first and second image signals are used as the “left-eye image” and the “right-eye image”, respectively, so as to view a three-dimensional image.
Similarly, there has been proposed a technique in which a plurality of micro lenses are formed on a solid-state image pickup device, and a plurality of photo diodes are disposed for each of the micro lenses (see e.g. PTL 2). In this technique, the plurality of photo diodes which are arranged in association with one micro lens are connected with each other via gates, and addition or non-addition of signals from the photo diodes arranged at adjacent locations is controlled.
In PTL 2, a picked-up image signal and a focus detection signal of the image pickup apparatus are obtained using the above-mentioned solid-state image pickup device, and hence during normal shooting, an image signal is generated by adding signals output from all of the photo diodes. To obtain signals having a parallax in the horizontal direction, photo diodes adjacent in the vertical direction are connected with each other, whereas to obtain signals having a parallax in the vertical direction, photo diodes adjacent in the horizontal direction are connected with each other. Then, according to an object image, focus detection is performed using a combination of added signals output from the photo diodes which is appropriate to focus detection of the object image.